Been a few years since I have been here but hopefully someone can help. My truck get up temp just fine, a/c is all brand new, all blend doors are fine, heater core was cleaned out, new radiator installed.

When i turn the selector to heat I have NO heat. All vents modes work fine. We even put in a newer control head! When the heat isnt working after a few hours or maybe even days all of a sudden out of nowhere the heat will start blow hot air. Or if I hit a significant bump it will blow hot hair.

I have had the dash apart in shops several times and the last shop replaced everything and nothing helps.

 

Did you try this? A lot of people, my self included, just turn the temperature control **** all the way over to HEAT, or all the way over to COLD when using it. I was having the same problem, when I found out doing so causes the contacts there to burn in that one spot, when set to high. Try turning the control **** back just a little, and see if that helps. It worked for me. Give it a try.

 

Xs 2! Worked for me too!!